[0001] The foregoing abstract is not to be taken as limiting the invention of this application,
and in order to understand the full nature and extent of the technical disclosure
of the application, reference must be made to the accompanying drawings and the following
detailed description.
[0002] The invention relates to a tire with a reinforcing belt structure, and more particularly
to a reinforcing belt structure which comprises two folded belt plies folded in the
same radially outward direction. The main body portions of these plies are of substantially
equal width and the unfolded end of the main body portion of the radially outer ply
lies within the space formed by the fold of the radially inner ply.
[0003] For the purposes of this invention, a folded belt ply is a ply which is folded along
a fold line to form a skirting which is substantially less than the width of the main
body portion of the ply .which has not been folded. Generally, the skirting is in
the range of approximately 1/5 to 1/3 of the width of the main body portion. Hereinafter
the skirting will be called the folded end portion of the ply, whereas the rest of
the ply will be called the main body portion of the ply.
[0004] Belt structures having two folded belt plies are known in the prior art and are exemplified
by German DOS 25 53 892. These structures are placed in the crown region of the tire
between the carcass structure and the tread band. The folds of the plies are located
in the shoulder regions of the tire. The first ply as seen from the carcass toward
the tread, that is, the radially innermost ply with respect to the axis of rotation
of the tire, forms the fold which envelops the unfolded end of the main body portion
of the second ply, that is, the radially outermost ply. As a consequence-of the folded
ends of the plies, a three ply layer assembly is formed in the border regions of the
belt structure. Where the belt plies comprise cords, it is common for the cords of
each ply to extend relative to the mid-circumferential centerplane of the.tire at
an angle or sign opposite to that of any next adjacent ply, thus in one border region
of the belt structure, the cords of the plies run alternately in opposite directions,
whereas in the other border region, the cords of the two outer plies run necessarily
in the same direction. This makes one border region stiffer than the other and causes
uneven tread wear.
[0005] The present invention provides a belt structure with a symmetrical orientation of
cords in the border regions whereby the disadvantage mentioned above is avoided.
SUMMARY OF THE INVENTION
[0006] The invention is characterized in that the cords. of the two folded plies have the
same cord orientation with respect to the mid-circumferential plane of the tire, and
that an unfolded ply of oppositely oriented cords and of a width substantially equal
to the main body portions of the folded plies is interposed between the main body
portions of the folded plies. Preferably, the cords of the unfolded middle ply are
composed of a material which is different from the cords of the folded plies. Whereas
the folded plies, for reasons of symmetry, have to be made of the same material, the
third ply can be made of a different material for reasons of tire handling characteristics,
tire weight and economics.
[0007] To acquaint persons skilled in the arts most closely related to the present invention,
certain preferred embodiments thereof illustrating a best mode now contemplated for
putting the invention into practice are described herein by and with reference to
the annexed drawings forming a part of the specification. The embodiments'shown and
described herein are illustrative and as will become apparent to those skilled in
these arts can be modified in numerous ways within the spirit and scope of the invention
defined in the claims hereof.
DESCRIPTION OF THE DRAWINGS
[0008]
Figure 1 is a cross-sectional view of a pneumatic tire embodying a belt reinforcing
structure made in accordance with the present invention; and
Figure 2 is a fragmentary plan view of the belt structure of Figure 1 in which some
parts are broken away to show the direction of the ply cords; and
Figures 3 and 4 are diagrammatical representations of the preferred embodiments of
the belt reinforcing structure of the present invention; and
Figure 5 is an enlarged fragmentary cross-sectional view of a lateral region of the
belt structure of Figure 1.
DETAILED DESCRIPTION OF THE INVENTION
[0009] Referring to Figure 1, there is illustrated a pneumatic tire 1 which comprises a
carcass, preferably of the radial type wherein the cords 2 of the carcass lie at an
angle in the range of 70° to 90° with respect to the mid-circumferential centerplane
of the tire 1. In the particular embodiment illustrated, the carcass is illustrated
as comprising one ply, however, the carcass may have any desired number of plies.
Over the radially outer peripheral region of the carcass is placed a first folded
ply 3, which extends circumferentially about the tire. Folded ply 3 comprises a main
body portion 4 and a folded end portion 5 which is folded radially outwardly of the
main body portion 4 forming bight 6. The width of the folded end portion 5 lies in
the range of 1/5 to 1/3 of the width of the main body portion 4. The cords of ply
3 lie at an angle between 15° and 25° with respect to the mid-circumferential plane
CP of the tire. The main body portion 4 of belt ply 3 extends substantially across
the width of the ground-engaging tread portion of the tire, generally terminating
in shoulder regions 14 and 15.
[0010] The belt structure further includes an unfolded belt reinforcing ply 7 which is placed
radially outwardly with respect to the axis of rotation of the tire from the first
folded ply 3. The width of the ply 7 is substantially equal to the width of the main
body portion 4 of ply 3. The lateral edge 8 of the ply 7 which is adjacent to the
folded end portion 5 lies within the bight 6. The other lateral edge 9 of ply 7 extends
to within approximately 10 mm of the lateral edge 10 of ply 3 giving staggered endings
of plies 3 and 7. The cords of ply 7 preferably lie at an angle of between 15° and
35° with respect to the mid-circumferential plane of the tire.
[0011] The belt structure further comprises a third ply 11 which is disposed radially outwardly
with respect to the axis of rotation of the tire to ply 7. The ply 11 has one end
12 folded radially outwardly back upon the main body portion 13 of ply 11. The width
of the folded end portion 12 lies in the range of 1/5 to 1/3 of the width of the main
body portion 13. The width of the main body portion 13 is substantially equal to the
width of ply 7. The folded end portion 12 of ply 11 is situated in the shoulder 14
axially opposite to shoulder 15 in which the folded end portion 5 of ply 3 is situated.
The lateral edge. 16 of the main body portion 13 of ply 11 extends into bight 6. The
axially outer edge 18 of folded end portion 12 of ply 11 extends axially outwardly
beyond the edge 10 of the main body portion 4 of ply 3 a-distance of approximately
5 mm.
[0012] The cords of ply 11 lie at an angle of between 15° and 25° to the mid-circumferential
centerplane CP of the tire.
[0013] In the particular embodiment illustrated, the cords of plies 3 and 11 lie at an angle
of about 20° and the cords of the belt ply 7 lie at an angle of approximately 25°.
[0014] Referring to Figure 2, there is shown a plan view of the belt structure of the invention
illustrating the relative angles of orientation of the different cords with respect
to the mid-circumferential centerplane CP. Figure 2 illustrates quite clearly that
the cords of the main body portion 4 of ply 3, unfolded ply 7, and main body portion
13 of ply 11 run in the relationship right-left-right, respectively. A right-oriented
ply is a ply which to an observer placed outside the tire has cords running in a direction
contained within the first and third quadrant defined by two Cartesian axes. Similarly
a left-oriented ply is a ply which to an observer placed outside the tire has cords
running in a direction contained within the second and fourth quadrant defined by
two Cartesian axes. The former orientation is also sometimes referred to as a Z orientation,
whereas the latter orientation is called a S orientation. In the border regions of
the belt structure where the folded end portions 5 and 12 are located the cords beginning
from the first ply 3 continuing radially outwardly to the folded portions run in the
relationship of right-left-right-left, respectively. It is understood that the present
invention is not limited to the above relationship, but may have the alternative relationship,
for example, left-right-left in the central portion of the belt structure and left-right-left-right
in the border regions.
[0015] In a preferred embodiment of the invention, the material used for the cords of the
unfolded ply 7 is different from the material of the cords of plies 3 and 11.
[0016] Figures 3 and 4 illustrate the belt structure wherein the cords of middle ply 7 are
made of a material different from that of the cords of plies 3 and 11. Figure 3 illustrates
the use of metal cords preferably steel cords, for folded plies 3 and 11. The unfolded
ply 7 comprises cords composed of a high modulus non-metallic fiber. The unfolded
plies can also comprise relatively fine steel cords as opposed to the coarser steel
cords of the folded plies.
[0017] Alternatively, Figure 4 illustrates a structure wherein the unfolded ply 7 comprises
cords of steel, while folded plies 3 and 11 comprise cords of a high modulus non-metallic
fiber. Folded plies 3 and 11 can also comprise relatively fine steel cords as opposed
to the coarser steel cords used for the unfolded ply 7.
[0018] The following materials are examples of high modulus non-metallic fibers which could
be used in the manufacture of cords: aramid, fiberglass, .carbon, silicon, and boron.
The present invention however is not limited to the use of these materials.
[0019] Reference is now being made to Figure 5. To avoid piled ply endings, whereby edges
18 and 10 of respective plies 11 and 7 would be contained in the same circumferential
plane, it is preferred that the axially outer edge 18 of folded end portion 12 extends
axially beyond the free edge 10 of ply 3 a distance S, the distance S being within
the range of about 5 mm to 10 mm, depending on the type of tire construction. It is
a further advantage if the edge 9 of ply 7 which is situated next to the folded edge
18 of ply 11 does not extend axially beyond the edge 10 of ply 3. Preferably, the
edge 9 is spaced axially inward from edge 10 a distance W. The distance W preferably
lies within the range of 5 mm to 10 mm, depending on the type of tire construction.
1. A tire with a reinforcing belt structure which comprises a first reinforcing folded
belt ply, said first folded belt ply comprising a main body portion and a single fblded
end portion disposed radially outwardly with respect to the axis of rotation of said
tire of said main body portion, a second reinforcing belt ply having a main body portion
and a single folded end portion disposed radially outwardly with respect to the axis
of rotation of said tire of said main body portion of said second ply, said second
ply being disposed radially outwardly of said first ply and oriented such that the
lateral end portion of the main body portion of said second ply lies within the space
formed by the folded end portion of said first ply, characterized in that the cords
of said first and second plies lie in the same orientation with respect to the mid-circumferential
centerplane of the tire, a middle unfolded belt ply of oppositely disposed oriented
cords and of a width substantially equal to the main body portions of said first and
second plies is disposed between the unfolded portions of said first and second plies.
2. A tire according to claim 1 further characterized in that said first and second
folded plies comprise cords made out of steel and said middle unfolded ply comprises
cords made out of a high modulus non-metallic fibre.
3. A tire according to claim 1 further characterized in that said first and second
folded plies comprise cords made out of a high modulus non-metallic fibre and that
the middle unfolded ply comprises of cords made of steel.
4. A tire according to claim 1 further characterized in that said first and second
folded plies comprise relatively fine steel cords and that said middle unfolded ply
comprises steel cords of relatively coarse steel.
5. A tire according to claim 1 further characterized in that said first and second
folded plies comprise relatively coarse steel cords and that said middle unfolded
ply comprises cords of relatively fine steel.
6.. A tire according to claims 1, 2, 3, 4 or 5 further characterized in that the distance
separating the lateral edge of the unfolded end portion of said first folded ply and
the folded edge of said second folded ply lies between 5 mm and 10 mm.
7. A tire according to claims 1, 2, 3, 4 or 5 further characterized in that the distance
separating the edge of the unfolded middle ply, which is situated next of the folded
edge of said second folded ply, and the edge of the unfolded end portion of said first
folded ply lies between 5 mm and 10 mm.
8. A tire according to claims 1, 2, 3, 4 or 5 further characterized in that the orientation
of the cords of the plies in the border regions of said reinforcing belt structure
with respect to the mid-circumferential plane is left-right-left-right starting from
the inner ply proceeding to the outer ply.
9. A tire according to claims 1, 2, 3, 4 or 5 further characterized in that the orientation
of the cords of the plies in the border regions of said reinforcing belt structure
with respect to the mid-circumferential plane is right-left-right-left starting from
the inner ply proceeding to the outer ply.
10. The tire according to claims 1, 2, 3, 4 or 5 further characterized by radial reinforcing
carcass structure.